Oscillator/mixer circuit

ABSTRACT

The invention relates to an oscillator circuit and a mixer circuit that, in part, contain the same components. The mixer circuit comprises at least two switch elements. The outputs of said switch elements are each coupled in a crosswise manner to the control inputs of the respective other switch element via a feedback element. The feedback element is disposed of in such a way to additionally enable an oscillatory operation of the oscillator/mixer circuit.

[0001] The invention relates to an oscillator/mixer circuit.

[0002] Such an oscillator/mixer circuit for processing analog signals isknown in the form of a series circuit for an oscillator circuit with amixer circuit.

[0003] In analog circuit technology, a voltage-controlled oscillator isused for producing a signal of a frequency prescribed by setting thedimensions of the oscillator circuit. Using a mixer circuit,particularly a switching mixer, such as a Gilbert cell, a signal to bemixed is mixed with a local oscillator signal, as explained in moredetail below, i.e. frequency conversion is performed for the signalwhich is to be mixed.

[0004] Both a voltage-controlled oscillator and a switching mixer in amicroelectronic circuit are currently used in a large number ofappliances and systems, for example for wireless radio transmission ofinformation, such as in a mobile radio system, a GPS receiver and atelevision satellite receiver.

[0005]FIG. 2 shows the basic design of a normal oscillator 200, as usedin microelectronics.

[0006] The oscillator 200 has a differential multivibrator 201 havingtwo MOS field-effect transistors 202, 203. In addition, the oscillator200 shown in FIG. 2 has a resonator element 204, 205 and also at leastone voltage-controlled tuning element 206, 207. The voltage-controlledtuning element 206, 207 is also simply called a tuning element.

[0007]FIG. 3 shows a basic circuit for an oscillator based on the priorart.

[0008] The oscillator 300 is in the form of an RC oscillator and has twoMOS field-effect transistors 304, 305 coupled to an input 301 via theirrespective gate connection 302, 303. The source connection and the drainconnection of the first MOS field-effect transistor 304 are connectedtogether and are coupled to a first output 306. The drain connection andthe source connection of the second MOS field-effect transistor 305 arelikewise coupled to one another and to a second output 307 of theoscillator 300.

[0009] The first output 306 is coupled to the gate connection 309 of athird transistor 310 via a first capacitor C 308.

[0010] The second output 307 is coupled to the gate connection 312 of afourth transistor 313 via a second capacitor C 311.

[0011] The gate connection 309 of the third transistor 310 is alsocoupled to the supply connection 315, to which the operating voltageV_(DD) for the oscillator circuit 300 can be applied, via a firstelectrical resistor R1 314. In addition, the gate connection 309 of thethird transistor 310 is coupled to the ground potential via a secondelectrical resistor R2 316, which allows the operating point of theoscillator circuit 300 to be set.

[0012] The gate connection 312 of the fourth transistor 313 is connectedto the supply connection 315 via a third electrical resistor R1 317 andalso likewise to the ground potential via a fourth electrical resistor318.

[0013] In addition, the drain connection of the third transistor 310 iscoupled to the supply connection 315 via a fifth electrical resistor319, and the drain connection of the fourth transistor 313 is coupled tothe supply connection 315 via a sixth electrical resistor 320. The fifthelectrical resistor 319 and the sixth electrical resistor 320 are loadresistors.

[0014] In addition, the source connections of the third transistor 310and of the fourth transistor 313 are coupled to the ground potential.

[0015]FIG. 4 shows the design of a normal Gilbert cell 400, which is anexample of a switching mixer, i.e. of a mixer circuit which, asdescribed below, has two transistors, in general terms two switchelements, which are each operated by virtue of the transistors beingturned on and off. In addition, the normal Gilbert cell 400 has ananalog input transistor.

[0016] The Gilbert cell 400 has a first switching transistor 401 and asecond switching transistor 402.

[0017] The gate connection 403 of the first switching transistor iscoupled to a first local oscillator input 404. The first localoscillator input 404 has a first local oscillator signal LO+ applied toit which is thus applied to the gate connection 403 of the firstswitching transistor 401, in order to control it by means of the localoscillator signal LO+, i.e. to turn it on and off.

[0018] The drain connection 405 of the first switching transistor 401 iscoupled to a first output 406. In addition, the drain connection 405 ofthe first switching transistor 401 is coupled to a supply connection 408via a first electrical resistor 407 as a mixer load resistor. The supplyconnection 408 can have the operating voltage V_(DD) for operating themixer circuit 400 applied to it.

[0019] Connected to the gate connection 409 of the second switchingtransistor 402 is a second local oscillator connection 410 to which asecond local oscillator signal LO− can be applied for controlling thesecond switching transistor 402. The second local oscillator signal LO−is shifted through 180° with respect to the first local oscillatorsignal LO+.

[0020] The drain connection 411 of the second switching transistor 409is coupled to a second output 412 and also to the supply connection 408via a second electrical resistor 413 as a mixer load resistor.

[0021] The source connections 414, 415 of the first switching transistor401 and of the second switching transistor 402 are coupled to the drainconnection 417 of an analog input transistor 418. The gate connection419 of the input transistor 418 is coupled to a mixing signal input 420to which the analog input signal ZE to be mixed can be applied. Thesource connection 421 of the input transistor 418 is coupled to theground potential.

[0022] In order to form an oscillator/mixer circuit from the knowncircuits described above, i.e. the oscillator circuit 300 and the mixercircuit 400, it is known practice to connect these circuits in series,i.e. a known oscillator/mixer circuit 500 (cf. FIG. 5) has theoscillator circuit 300 described in FIG. 3 and the mixer circuit 400described in FIG. 4, which are connected to one another in series suchthat the first output 306 of the oscillator 300 is coupled to the firstlocal oscillator input 404 of the mixer circuit 400 via a firstelectrical connection 501. The second output 307 of the oscillatorcircuit 300 is coupled to the second local oscillator input 410 of themixer circuit 400 via a second electrical coupling 502. The localoscillator signals are shifted through 180° with respect to one another.

[0023] The known oscillator/mixer circuit 500 has several drawbacks.

[0024] Connecting two complete, essentially mutually independentcircuits, i.e. the oscillator circuit 300 and the mixer circuit 400, inseries requires a relatively large number of electrical components, i.e.a relatively large number of electrical resistors and transistors,normally MOS field-effect transistors. Integration of the knownoscillator/mixer circuit 500 on a chip thus has a considerablerequirement in terms of chip area in order to implement it.

[0025] Another considerable drawback of the oscillator/mixer circuit 500can be seen in that two electrical connections 501, 502 are requiredbetween the circuit components, i.e. the oscillator circuit 300 and themixer circuit 400.

[0026] Particularly in the area of very high-frequency applications, theelectrical connections 501, 502 represent a considerable restriction interms of their usability on account of the very high attenuation towhich the output signal produced at the outputs 306, 307 of theoscillator circuit is subject before it reaches the inputs 404, 410 ofthe mixer circuit 400. In the case of a very high-frequency applicationin which a signal frequency in a range of approximately 1 GHz to severaltens of GHz, preferably up to 77 GHz and above, is required, thisresults in such an oscillator/mixer circuit 500 barely being able to beused, since no signal with sufficient signal amplitude is applied to,i.e. arrives at, the local oscillator inputs 404, 410 of the mixercircuit 400.

[0027] In addition, particularly within the scope of implementing theoscillator/mixer circuit 500 as an integrated circuit, the “matching”problem is of great significance on account of the physical distancesbetween the individual components of the circuit, since it is aconsiderable problem, technologically, to produce the components whichare to be used with sufficient similarity over a relatively longdistance from one another on a chip or on a wafer. This means that thecomponents are frequently matched to one another only with greatdifficulty and sometimes not at all, resulting in an oscillator/mixercircuit 500 which works only poorly or not at all.

[0028] It is also known practice to use a diode or an electrical circuitcontaining a diode as a mixer circuit or as an oscillator circuit,where, in such a case in which a mixer circuit's mixing is based on anactive component, mixing of the signals which are to be mixed is basedon the nonlinear characteristic curve of an active component, in thespecific case of the diode.

[0029] The invention is thus based on the problem of specifying anoscillator/mixer circuit which has a reduced area requirement, whenproducing it on a chip, as compared with the known oscillator/mixercircuit and where the oscillator/mixer circuit's mixer circuit is notbased on the use of the nonlinear characteristic curve of an activecomponent.

[0030] The problem is solved by the oscillator/mixer circuit having thefeatures of the independent patent claim.

[0031] The oscillator/mixer circuit has an oscillator circuit and amixer circuit. The oscillator circuit and the mixer circuit have thesame components to some extent.

[0032] Expressed in other words, this means that the same components inthe oscillator/mixer circuit are used both for frequency generation andfor the mixing operation.

[0033] In addition, the mixer circuit has at least a first switchelement and a second switch element, where an output of the first switchelement is coupled to a control input of the second switch element via afirst feedback element. An output of the second switch element iscoupled to a control input of the first switch element via a secondfeedback element. The feedback elements are set up such that oscillatoroperation of the oscillator/mixer circuit is made possible.

[0034] Oscillator operation of the oscillator/mixer circuit is ensured,by way of example, by virtue of oscillation buildup being ensured in theoscillator circuit in the oscillator/mixer circuit, which can beachieved, by way of example, by virtue of the feedback elements ensuringthat the control signals applied to the control inputs of the switchelements are certain to have a phase angle which is suitable for theoscillator circuit's respective circuit type, and also a loop gain ofgreater than 1.

[0035] Expressed clearly, this means that the oscillator/mixer circuithas an oscillator circuit and a mixer circuit which have commoncomponents and where the mixer elements are in the form of a switchingmixer, i.e. in the form of a circuit which normally has at least twotransistors operated in turn-on mode and turn-off mode.

[0036] This ensures that the mixing of signals in the oscillator/mixercircuit is not based on a nonlinear characteristic curve of an activecomponent.

[0037] The oscillator circuit can also be set up as an LC oscillatorcircuit.

[0038] In this case, in one refinement of the invention, a respectiveinductor is coupled to the output of the first switch element and to theoutput of the second switch element, and the input of the first switchelement is coupled to the input of the second switch element and to amixing signal input to which a signal to be mixed can be applied.

[0039] Clearly, the oscillator/mixer circuit can thus be regarded as anoscillator circuit in which the ground connection and the sourceconnections of the oscillator transistors in the oscillator circuit havean input transistor connected between them whose gate connection iscoupled to the mixing signal input. In general terms, the drainconnections of the oscillator transistors and the ground connection havean input transistor connected between them whose control input iscoupled to the mixing signal input.

[0040] Thus, an oscillator/mixer circuit has been provided which has asignificantly reduced number of required components and cansimultaneously be operated as an oscillator circuit and as a mixercircuit.

[0041] The compact design and the, to some extent, common use of somecomponents both by the oscillator circuit and by the mixer circuit inthe oscillator/mixer circuit result in a significant reduction inrequired chip area for integrating the oscillator/mixer circuit.

[0042] In addition, the compact design of the oscillator/mixer circuitmeans that it is very well suited to a radio-frequency application, inparticular, since the signals to be processed need to coversignificantly reduced distances over electrical lines as compared withthe known oscillator/mixer circuit described above, and are thus subjectto significantly reduced attenuation.

[0043] In addition, the matching problem for the components used isavoided.

[0044] In one refinement of the invention, an analog input transistor isconnected between the inputs of the switch elements and the mixingsignal input, with the mixing signal input being coupled to the controlinput of the input transistor.

[0045] In accordance with an alternative refinement of the invention,provision is also made for the oscillator circuit to be in the form ofan RC oscillator circuit.

[0046] In this refinement, there is also a first electrical resistorwhich is connected between the control input of the first switch elementand a supply connection, to which supply connection an operating voltageV_(DD) for the oscillator/mixer circuit can be applied. A secondelectrical resistor is connected between the control input of the firstswitch element and the input of the first switch element, and a thirdelectrical resistor is connected between the control input of the secondswitch element and the supply connection. A fourth electrical resistoris connected between the control input of the second switch element andthe input of the second switch element. In addition, in this refinementof the invention, the input of the first switch element is coupled tothe input of the second switch element and also to a mixing signal inputto which a signal which is to be mixed can be applied.

[0047] In accordance with this refinement of the invention, provision ispreferably made for the first electrical resistor and the thirdelectrical resistor to be dimensioned in the same way, and for thesecond electrical resistor and the fourth electrical resistor to begiven the same dimensions.

[0048] A further switch element can be connected between the inputs ofthe switch elements and the mixing signal input, with the mixing signalinput being coupled to a control input of the input transistor.

[0049] In another refinement of the invention, the feedback elements areset up such that the phase angle of the signals applied to therespective control input can be set.

[0050] In addition, the feedback elements can be set up asfrequency-determining elements of the oscillator/mixer circuit.

[0051] Within the context of this description, the expression“frequency-determining element” is to be understood to mean that such anelement can be used to set the oscillation frequency of the oscillatorcircuit.

[0052] The first feedback element and the second feedback element caneach have a capacitor, preferably a capacitor whose capacitance can berespectively varied, preferably using a control voltage.

[0053] The first switch elements and/or the second switch element caneach have a transistor or can be formed by a transistor.

[0054] In another refinement of the invention, at least some of thecomponents are produced using CMOS technology.

[0055] Exemplary embodiments of the invention are illustrated in thefigures and are explained in more detail below.

[0056] In the drawings,

[0057]FIG. 1 shows an oscillator/mixer circuit according to a firstexemplary embodiment of the invention;

[0058]FIG. 2 shows a basic illustration of a radio-frequency oscillator;

[0059]FIG. 3 shows an oscillator circuit according to the prior art;

[0060]FIG. 4 shows a basic circuit for a Gilbert cell according to theprior art;

[0061]FIG. 5 shows an oscillator/mixer circuit according to the priorart;

[0062]FIG. 6 shows an oscillator/mixer circuit according to a secondexemplary embodiment of the invention; and

[0063]FIG. 7 shows an oscillator/mixer circuit according to a thirdexemplary embodiment of the invention.

[0064]FIG. 1 shows an oscillator/mixer circuit 100 according to a firstexemplary embodiment of the invention.

[0065] The oscillator/mixer circuit 100 has an oscillator circuit 101(symbolized using dashed lines in FIG. 1) and a mixer circuit 102(symbolized using dashes and dots in FIG. 1).

[0066] As FIG. 1 shows, some components in the oscillator/mixer circuit100 are contained both in the oscillator circuit 101 and in the mixercircuit 102.

[0067] The oscillator/mixer circuit 100 has a first switching transistor103 and a second switching transistor 104.

[0068] The drain connection 105 of the first switching transistor 103 iscoupled to a first output 106 of the oscillator/mixer circuit 100. Whenthe oscillator/mixer circuit 100 is in mixing mode, the first output 106provides a first output signal OUT+, which is also referred to as afirst intermediate frequency signal OUT+ in downward mixing mode.

[0069] In addition, the first output 106 and the drain connection 105 ofthe first switching transistor 103, as switch output for the firstswitch element, are coupled to a first connection 107 of a firstcapacitor 108 as a first feedback element. A second connection 109 ofthe first capacitor 108 is coupled to the gate connection 110 of thesecond switching transistor 104.

[0070] The drain connection 111 of the second switching transistor 104,as switch output for the second switch element, is coupled to a secondoutput 112 of the oscillator/mixer circuit 100. When theoscillator/mixer circuit 100 is in mixer mode, the second output 112provides a second output signal, which is also referred to as secondintermediate frequency signal OUT− in downward mixing mode.

[0071] The phase angle of the second output signal is shifted through180° with respect to that of the first output signal.

[0072] In addition, the drain connection 111 of the second switchingtransistor 104 is coupled to a first connection 113 of a secondcapacitor 114 as a second feedback element. A second connection 115 ofthe second capacitor 114 is coupled to the gate connection 116 of thefirst switching transistor 103.

[0073] The source connection 117 of the first switching transistor 103,as switch input for the first switch element, is coupled to the sourceconnection 118 of the second switching transistor 104, as switch inputfor the second switch element, and also to the drain connection 119 ofan input transistor 120, which is no longer a functional element of theoscillator circuit 101, but is a functional element of the mixer circuit102.

[0074] The gate connection 121 of the input transistor 120 is coupled toa mixing signal input 122 to which a normally analog input signal ZEwhich is to be mixed can be applied.

[0075] The source connection 123 of the input transistor 120 is coupledto the ground connection 124.

[0076] Expressed another way, this means that the drain connections,i.e. clearly the outputs of the two switching transistors 103, 104, arefed back crosswise via a respective capacitor 108 or 114 to the gateconnections 110, 116 of the respective other switching transistor 103,104.

[0077] This clearly means that the mixer circuit 102, in comparison withthe mixer circuit according to the prior art, which has a diode asmixing element, inventively uses a switching mixer which involves therespective switching transistors 103, 104 respectively turning oneanother on and off in antiphase.

[0078] Expressed another way, this means that, if the first switchingtransistor 103 is on, the second switching transistor 104 is in adeactivated state on account of the feedback via the first capacitor 108to the gate connection 110 of the second switching transistor 104. Ifthe second switching transistor 104 is in an activated state, the firstswitching transistor 103 is in a deactivated state on account of thefeedback via the second capacitor 114 to the gate connection 116 of thefirst switching transistor.

[0079] The drain connection 105 of the first switching transistor 103 isalso coupled to a supply connection 126, to which the operating voltageV_(DD) for the oscillator/mixer circuit 100 can be applied, via a firstelectrical resistor 125.

[0080] The supply connection 126 likewise has the drain connection 111of the second switching transistor 104 coupled to it via a secondelectrical resistor 127.

[0081] In addition, the gate connection 116 of the first switchingtransistor and the second connection 115 of the second capacitor 114 arecoupled to a first connection 128 of a third electrical resistor 129 andvia the latter to the supply connection 126.

[0082] In addition, the gate connection 116 of the first switchingtransistor and the second connection 115 of the second capacitor 114 arecoupled to the ground connection 124 via a first connection 130 of afourth electrical resistor 131 and via the latter.

[0083] The gate connection 110 of the second switching transistor 104and the second connection 109 of the first capacitor 108 are coupled toa first connection 132 of a fifth electrical resistor 133 and via thelatter to the supply connection 126.

[0084] In addition, the gate connection 110 of the second switchingtransistor 104 and the second connection 109 of the first capacitor 108are coupled to a first connection 134 of a sixth electrical resistor 135and via the latter to the ground connection 124.

[0085]FIG. 6 shows an oscillator/mixer circuit 600 according to a secondexemplary embodiment of the invention.

[0086] In accordance with the second exemplary embodiment of theinvention, the oscillator circuit is set up as an LC oscillator circuit.

[0087] The oscillator/mixer circuit 600 has a first switching transistor601 and a second switching transistor 602.

[0088] The drain connection 603 of the first switching transistor 601 iscoupled to a first output 604 of the oscillator/mixer circuit 600, andthe drain connection 605 of the second switching transistor 602 iscoupled to a second output 606 of the oscillator/mixer circuit 600.

[0089] In addition, the drain connection 603 of the first switchingtransistor 601 is coupled to the gate connection 608 of the secondswitching transistor 602 via a first capacitor 607 as a first feedbackelement, and the drain connection 605 of the second switching transistor602 is coupled to the gate connection 609 of the first switchingtransistor 601 via a second capacitor 608 as a second feedback element.

[0090] This again achieves crosswise feedback of the respective outputsof the switching transistors, as switch elements of the oscillator/mixercircuit 600, to the respective control inputs, i.e. the gate connectionsof the respective other switching transistor.

[0091] In addition, the drain connection 603 of the first switchingtransistor 601 is coupled to a first connection 610 of a first inductor611 and via the latter to a supply connection 612 of theoscillator/mixer circuit 600.

[0092] The drain connection 605 of the second switching transistor 602is additionally coupled to a first connection 613 of a second inductor614 and via the latter likewise to the supply connection 612.

[0093] In addition, the source connection 615 of the first switchingtransistor 601 and the source connection 616 of the second switchingtransistor 602 are coupled to one another and to a drain connection 617of an input transistor 618, whose source connection 619 is coupled tothe ground connection 620.

[0094] The source connection 621 of the input transistor 619 is coupledto a mixing signal input 622 of the oscillator/mixer circuit 600.

[0095] The capacitors for the feedback elements described above both inthe oscillator/mixer circuit 100 based on the first exemplary embodimentand in the oscillator/mixer circuit 600 based on the second exemplaryembodiment are set up such that a respective phase shift of 180° isensured for the respective electrical analog signals applied to the gateconnections of the switching transistors.

[0096]FIG. 7 shows, as a third exemplary embodiment, twoseries-connected mixer/oscillator circuits according to the firstexemplary embodiment or according to the second exemplary embodiment,which are coupled to each other via a phase shifter element 701 which isset up such that the phase of an output signal 702 produced at an outputof the first oscillator/mixer circuit is shifted through 90° withrespect to the input signal 703 applied to the input of the secondoscillator/mixer circuit.

[0097] In this way, an oscillator/mixer circuit 700 providing a total offour output signals is specified whose output signals are each shiftedthrough 90° with respect to one another.

[0098] In the two exemplary embodiments described above, the componentsare produced using CMOS technology, i.e. the transistors used, inparticular, are CMOS field-effect transistors.

[0099] The implementations described above thus mean that the mixercircuit and the oscillator circuit are clearly no longer circuits whichare physically separate from one another; instead, the same componentsare largely used both for the mixer circuit and for the oscillatorcircuit.

[0100] Hence, if component tolerances are produced in theoscillator/mixer circuit, these affect both the operation of the mixercircuit and that of the oscillator circuit in the same way, and themixer circuit and the oscillator circuit thus remain ideally matched toone another.

[0101] On account of the saving on the connecting lines, required in anoscillator/mixer circuit according to the prior art, between theoscillator circuit and the mixer circuit (cf. FIG. 5, connecting lines501, 502), the inventive oscillator/mixer circuit is particularlysuitable for use in very high-frequency technology, particularly as atransmitter and/or receiver. A suitable frequency range for operatingthe inventive oscillator/mixer circuit is preferably in the order ofmagnitude of one to several 10 GHz, which means that theoscillator/mixer circuit can be used suitably for wireless radiotransmission, for example as a mobile radio transmitter or mobile radioreceiver, as a radar transmitter or radar receiver or as a receiver fora global positioning system (GPS).

[0102] The invention can clearly be seen as being that an oscillatorcircuit unit and a mixer circuit unit have, to some extent, the samecomponents in order to perform their respective function. The mixercircuit has at least two switch elements. The latter's outputs are isrespectively coupled crosswise to the control inputs of the respectiveother switch element via a respective feedback element. The feedbackelement is respectively set up such that oscillator operation of theoscillator/mixer circuit is additionally made possible.

[0103] It should be noted in this context that the oscillator/mixercircuit can be set up as an upward mixer or else as a downward mixer.

1. An oscillator/mixer circuit having an oscillator circuit, having amixer circuit in which the oscillator circuit and the mixer circuit havethe same components to some extent, in which the mixer circuit has atleast a first switch element and a second switch element, where anoutput of the first switch element is coupled to a control input of thesecond switch element via a first feedback element, where an output ofthe second switch element is coupled to a control input of the firstswitch element via a second feedback element, and where the feedbackelements are set up such that oscillator operation of theoscillator/mixer circuit is made possible.
 2. The oscillator/mixercircuit as claimed in claim 1, in which the oscillator circuit is set upas an LC oscillator circuit.
 3. The oscillator/mixer circuit as claimedin claim 2, in which a respective inductor is coupled to the output ofthe first switch element and to the output of the second switch element,and in which the input of the first switch element is coupled to theinput of the second switch element and to a mixing signal input to whicha signal to be mixed can be applied.
 4. The oscillator/mixer circuit asclaimed in claim 3, in which an input transistor is connected betweenthe inputs of the switch elements and the mixing signal input, with themixing signal input being coupled to a control input of the inputtransistor.
 5. The oscillator/mixer circuit as claimed in claim 1 or 2,in which the oscillator circuit is set up as an RC oscillator circuit.6. The oscillator/mixer circuit as claimed in claim 5, having a firstelectrical resistor, which is connected between the control input of thefirst switch element and a supply connection to which an operatingvoltage for the oscillator/mixer circuit can be applied, having a secondelectrical resistor, which is connected between the control input of thefirst switch element and the input of the first switch element, having athird electrical resistor, which is connected between the control inputof the second switch element and the supply connection, having a fourthelectrical resistor, which is connected between the control input of thesecond switch element and the input of the second switch element, and inwhich the input of the first switch element is coupled to the input ofthe second switch element and also to a mixing signal input to which asignal to be mixed can be applied.
 7. The oscillator/mixer circuit asclaimed in claim 6, in which a further switch element is connectedbetween the inputs of the switch elements and the mixing signal input,with the mixing signal input being coupled to a control input of theinput transistor.
 8. The oscillator/mixer circuit as claimed in one ofclaims 1 to 7, in which the feedback elements are set up such that thephase angle of the signals applied to the respective control inputs canbe set.
 9. The oscillator/mixer circuit as claimed in one of claims 1 to8, in which the feedback elements are set up as frequency-determiningelements.
 10. The oscillator/mixer circuit as claimed in one of claims 1to 9, in which the first feedback element and the second feedbackelement have a capacitor.
 11. The oscillator/mixer circuit as claimed inone of claims 1 to 10, in which the first switch element has atransistor, and in which the second switch element has a furthertransistor.
 12. The oscillator/mixer circuit as claimed in one of claims1 to 11, in which at least some of the components are produced usingCMOS technology.